Airworthiness Directives; General Electric Company CT7-5, -7, and -9 Series Turboprop Engines

[Federal Register Volume 72, Number 67 (Monday, April 9, 2007)]
[Rules and Regulations]
[Pages 17379-17381]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-6446]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20944; Directorate Identifier 2003-NE-64-AD; 
Amendment 39-15018; AD 2007-08-01]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CT7-5, -7, and 
-9 Series Turboprop Engines

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is superseding an existing airworthiness directive 
(AD) for General Electric Company (GE) CT7-5A2, -5A3, -7A, -7A1, -9B, -
9B1, and -9B2, -9C, -9C3, -9D, and -9D2 turboprop engines, with certain 
part number (P/N) and serial number stage 2 turbine aft cooling plates 
installed. That AD currently requires a onetime eddy current inspection 
(ECI) of boltholes in certain P/N stage 2 turbine aft cooling plates. 
This AD expands the population of affected CT7 turboprop engine models, 
but reduces the number of cooling plates affected. It also requires a 
onetime ECI of boltholes in certain P/N stage 2 turbine aft cooling 
plates with specific serial numbers. This AD results from the 
manufacturer expanding the list of affected engine models and 
identifying the affected stage 2 turbine aft cooling plates by serial 
number. We are issuing this AD to prevent separation of the stage 2 
turbine aft cooling plate, resulting in uncontained engine failure and 
damage to the airplane.

DATES: This AD becomes effective May 14, 2007. The Director of the 
Federal Register approved the incorporation by reference of certain 
publications listed in the regulations as of May 14, 2007.

ADDRESSES: You can get the service information identified in this AD 
from General Electric Aircraft Engines CT7 Series Turboprop Engines, 
1000 Western Ave, Lynn, MA 01910; telephone (781) 594-3140, fax (781) 
594-4805.
    You may examine the AD docket on the Internet at http://dms.dot.gov 
or in Room PL-401 on the plaza level of the Nassif Building, 400 
Seventh Street, SW., Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mark Bouyer, Engine Certification 
Office, FAA, Engine and Propeller Directorate, 12 New England Executive 
Park, Burlington, MA 01803; telephone (781) 238-7755; fax (781) 238-
7199.

SUPPLEMENTARY INFORMATION: The FAA proposed to amend 14 CFR part 39 
with a proposed AD. The proposed AD applies to GE CT7-5A2, -5A3, -7A, -
7A1, -9B, -9B1, and -9B2 turboprop engines, with certain P/N and serial 
number stage 2 turbine aft cooling plates installed. We published the 
proposed AD in the Federal Register on March 31, 2006 (71 FR 16248). 
That action proposed to expand the population of affected CT7 turboprop 
engine models required to undergo a onetime ECI of boltholes in certain 
P/N stage 2 turbine aft cooling plates. That action also proposed to 
reduce the number of cooling plates affected by identifying the serial 
numbers.

Examining the AD Docket

    You may examine the docket that contains the AD, any comments 
received, and any final disposition in person at the Docket Management 
Facility between 9 a.m. and 5 p.m., Monday through Friday, except 
Federal holidays. The Docket Office (telephone (800) 647-5227) is 
located on the plaza level of the Department of Transportation Nassif 
Building at the street address stated in ADDRESSES. Comments will be 
available in the AD docket shortly after the DMS receives them.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Clarification of ECI Requirements

    GE suggests that we clarify paragraph (f) of this AD to limit the 
required ECI to stage 2 turbine aft cooling plates that are being 
returned to service. This change would eliminate any requirement to ECI 
cooling plates that are not going to be reused. We agree. If the 
cooling plate is not going to be reused, there is no need to ECI it 
immediately after it is removed. Paragraph (h) of this AD requires an 
ECI of all cooling plates affected by this AD before they are returned 
to service. We made the clarification to paragraph (f).

[[Page 17380]]

Clarification of Onetime Inspection

    GE proposes that we add a terminating action statement to clarify 
that the ECI is a onetime inspection and repetitive inspections of the 
stage 2 turbine aft cooling plate is unnecessary. We do not agree. This 
information is already included in paragraph (f), which specifies that 
the inspection is a onetime ECI. We did not change the AD.

Question on Compliance Threshold of 6,000 Cycles-in-Service (CIS)

    GE also questions whether the calculated compliance threshold of 
6,000 CIS is viable given the amount of time required to publish the 
AD. We do not agree. The number of engine cycles that will accumulate 
during the AD review process will not change the safety assessment that 
is based on the calculated compliance time. We did not change the AD.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD with the changes described previously. 
We have determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    We estimate that this AD will affect 494 engines installed on 
airplanes of U.S. registry. We also estimate that it will take about 1 
work-hour per engine to perform the actions, and that the average labor 
rate is $80 per work-hour. Based on the number of cracks found in the 
inspected engines, we estimate that 2.5 percent of the 494 engines will 
require replacing stage 2 turbine aft cooling plates because of 
rejection by the onetime ECI. Required parts will cost about $17,000 
per engine. Based on these figures, we estimate the total cost of the 
AD to U.S. operators to be $243,520.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will not have a 
substantial direct effect on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and
    (3) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.
    We prepared a summary of the costs to comply with this AD and 
placed it in the AD Docket. You may get a copy of this summary at the 
address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the Federal Aviation Administration amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by removing Amendment 39-14247 70 FR 
54835, September 19, 2005, and by adding a new airworthiness directive, 
Amendment 39-15018, to read as follows:

2007-08-01 General Electric Company: Amendment 39-15018. Docket No. 
FAA-2005-20944; Directorate Identifier 2003-NE-64-AD.

Effective Date

    (a) This airworthiness directive (AD) becomes effective May 14, 
2007.

Affected ADs

    (b) This AD supersedes AD 2005-18-01, Amendment 39-14247.

Applicability

    (c) This AD applies to General Electric Company (GE) CT7-5A2/-
5A3/-7A/-7A1/-9B/-9B1/-9B2/-9C/-9C3/-9D/-9D2 turboprop engines with 
stage 2 turbine aft cooling plates, part number (P/N) 6064T07P01, 
6064T07P02, 6064T07P05, or 6068T36P01 installed. These engines are 
installed on, but not limited to, Construcciones Aeronauticas, SA 
CN-235 series and SAAB Aircraft AB SF340 series airplanes.

Unsafe Condition

    (d) This AD results from the manufacturer expanding the list of 
affected engine models and identifying the affected stage 2 turbine 
aft cooling plates by serial number. We are issuing this AD to 
prevent separation of the stage 2 turbine aft cooling plate, 
resulting in uncontained engine failure and damage to the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed at the next engine or hot section module shop visit, 
but before accumulating an additional 6,000 cycles-in-service after 
the effective date of the AD, unless already done.

Onetime Eddy Current Inspection (ECI)

    (f) Perform a onetime ECI of the stage 2 turbine aft cooling 
plates P/N 6064T07P01, 6064T07P02, 6064T07P05, or 6068T36P01, that 
are listed by serial number in Section 4, Appendix A, of GE Alert 
Service Bulletin (ASB) No. CT7-TP S/B 72-A0464, Revision 04, dated 
December 12, 2005, and that will be returned to service. Use 3.B.(1) 
through 3.B.(3) of GE ASB No. CT7-TP S/B 72-A0464, Revision 4, dated 
December 12, 2005 to perform the inspection.
    (g) For stage 2 turbine aft cooling plates that do not pass the 
Return to Service Criteria, do either of the following:
    (1) Replace the stage 2 turbine aft cooling plate with a new 
cooling plate that has a serial number that is not listed in Section 
4, Appendix A, of GE ASB No. CT7-TP S/B 72-A0464, Revision 04, dated 
December 12, 2005, or
    (2) Replace the stage 2 turbine aft cooling plate with a cooling 
plate that meets the acceptance criteria of 3.B.(1) through 3.B.(3) 
of GE ASB No. CT7-TP S/B 72-A0464, Revision 4, dated December 12, 
2005.
    (h) After the effective date of this AD, do not install any 
stage 2 turbine aft cooling plates with serial numbers identified in 
Section 4, Appendix A, without inspecting the cooling plate as 
specified in 3.B.(1) through 3.B.(3) of GE ASB No. CT7-TP S/B 72-
A0464 Revision 04, December 12, 2005.

Previous Credit

    (i) Eddy current inspections of the stage 2 turbine aft cooling 
plate boltholes done before the effective date of this AD that use 
GE ASB No. CT7-TP S/B 72-A0464, dated February 25, 2003; or Revision 
1, dated March 12, 2003; or Revision 2, dated May 9,

[[Page 17381]]

2003; or Revision 3, dated July 23, 2004, comply with the 
requirements specified in this AD.

Definition of Engine or Hot Section Module Shop Visit

    (j) For the purposes of this AD, an engine or hot section module 
shop visit is defined as the introduction of the engine or hot 
section module into a shop that includes separating major case 
flanges.

Alternative Methods of Compliance

    (k) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (l) Contact Mark Bouyer, Engine Certification Office, FAA, 
Engine and Propeller Directorate, 12 New England Executive Park, 
Burlington, MA 01803; e-mail: [email protected]; telephone (781) 
238-7755; fax (781) 238-7199, for more information about this AD.

Material Incorporated by Reference

    (m) You must use General Electric Alert Service Bulletin No. 
CT7-TP S/B 72-A0464, Revision 04, dated December 12, 2005, to 
perform the actions required by this AD. The Director of the Federal 
Register approved the incorporation by reference of this service 
bulletin in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
Contact General Electric Aircraft Engines CT7 Series Turboprop 
Engines, 1000 Western Ave, Lynn, MA 01910; telephone (781) 594-3140; 
fax (781) 594-4805 for a copy of this service information. You may 
review copies at the FAA, New England Region, Office of the Regional 
Counsel, 12 New England Executive Park, Burlington, MA; or at the 
National Archives and Records Administration (NARA). For information 
on the availability of this material at NARA, call 202-741-6030, or 
go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued in Burlington, Massachusetts, on April 2, 2007.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
 [FR Doc. E7-6446 Filed 4-6-07; 8:45 am]
BILLING CODE 4910-13-P

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